11.2.3.1. Water Availability

One-third of the world's renewable water resources (13,500 km3
yr-1 out of 42,700 km3 yr-1) are concentrated
in Asia (Shiklomanov, 2001). Water availability varies widely across the different
regions of Asia, howeverfrom 77,000 m3 yr-1 per
capita to less than 1,000 m3 yr-1 per capita. Table
11-7 provides available information on renewable local water resources,
water availability, and water use dynamics by natural-economic region of Asia.
The major share of Asian water resources (72%) is located in four countries:
Russia (3,107 km3 yr-1), China (2,700 km3 yr-1),
Indonesia (2,530 km3 yr-1), and India (1,456 km3
yr-1). Water resources of the two largest river systems of Asiathe
Ganges (with Brahmaputra and Meghna) and the Yangtze (Changjiang)attain
1,389 km3 yr-1 (794 x 103 m3 yr-1
km-2) and 1,003 km3 yr-1 (554 x 103 m3
yr-1 km-2). Figure 11-11 depicts
the spatial distribution of currently estimated annual mean surface runoff over
Asia. The runoff distribution within a year in Asia is most uniform in the rivers
of southeast Asia. Over the rest of the continent, more than half of the annual
runoff is discharged during the three summer months.

Water availabilityin terms of temporal as well as spatial distributionis
expected to be highly vulnerable to anticipated climate change. Growing populations
and concentration of population in urban areas will exert increasing pressures
on water availability and water quality. As reported in IPCC (1998), runoff
generally is expected to increase in the high latitudes and near the equator
and decrease in the mid-latitudes under anticipated climate change scenarios.

Table 11-7: Renewable local water resources, water
availability, and water-use dynamics, by natural-economic regions of Asia
(Shiklomanov, 2001).

Region

Area
(106 km2)

Water Resources
(km3 yr-1)

Potential Water Availability
(103 m3 yr-1)

Dynamics of Freshwater Use (km3 yr-1)a

Water Use as a Percentage of Water Resourcesa

Forecast

per km2

per capita

1900

1950

1995

2000

2010

2025

1995

2025

Siberia and far east of Russia

12.76

3107

243

76.6

0.7

5.6

30.6

30

32

38

1.0

1.2

0.4

1.3

15

15

17

21

0.5

0.6

North China and Mongolia

8.29

1029

124

2.13

37

98

254

273

305

373

24.7

36.2

30

75

182

182

194

210

17.7

20.4

South Asia

4.49

1988

443

1.77

201

367

932

969

1060

1370

43.6

64.1

160

293

687

710

767

944

32.1

44.2

Southeast Asia

6.95

6646

956

4.77

99

230

525

551

617

781

7.8

11.6

77

170

388

393

413

425

5.8

6.3

Western Asia

6.82

490

71.8

2.11

43

91

238

248

283

346

48.5

70.6

34

71

174

181

201

229

35.5

46.7

Central Asia and Kazakhstan

3.99

181

45.4

3.78

29

57

154

151

160

169

75.5

82.8

19

37

102

102

110

122

50.0

59.8

Transcaucasia

0.19

67.9

358

4.63

4.2

11.4

23.7

23

26

27

32.0

36.5

2.1

7.1

17.5

17

19

20

23.7

27.0

Total

43.50

13510

311

3.92

414

860

2157

2245

2483

3104

16.0

23.0

322

654

1565

1603

1721

1971

11.6

14.6

a Nominator = total
water withdrawal; denominator = water consumption.